Bony shapes

FIG. 6-2 Bony shapes. At this articulation, an ovoid shape sits in a sellar shape. Convex and concave surlaces are shown. 

In invertebrates, collagen is uncalcified, whereas in vertebrates it occurs in the form of soft and hard tissue. Remains of the earliest vertebrates — bony armour — are found in sediments of the Ordovician (ca. 500 million years). At about that time, conodonts appeared in the stratigraphic column mineralogically they are carbonate apatite. Conodonts are small tooth-shaped fossils 0.2 to 3 mm in size whose origin is in doubt they are most likely remains of some unknown chordata that became extinct in Triassic time516. ... 

The snail-shaped cochlea, located in the temporal bone of the skull, contains a bony labyrinth and a membranous labyrinth. The bony labyrinth consists of the otic capsule (the external shell) and the modiolus (the internal axis). The membranous labyrinth, coiled inside the bony labyrinth, consists of three adjacent tubes the scala vestibuli, the scala media, and the scala tympani (O Figure 4-1). The scala vestibuli and the scala media are separated by Reissner s membrane the scala media and the scala tympani are separated by the basilar membrane and part of the osseous spiral lamina. The scala vestibuli and the scala tympani are filled with perilymph, a fluid whose ionic composition is similar to that of cerebrospinal fluid. The fluid sealed inside the scala media, the endolymph, contains a high concentration of potassium. 

Apart from sharks, where the upper and lower teeth are relatively similar in shape and number, the upper and lower jaws of modern jawed vertebrates (gnathostomes) generally differ in the shape and number of their teeth or tooth-bearing dermal bones. In bony fishes (osteichthyans), and land vertebrates (tetrapods), this difference disappears as one considers early, Paleozoic groups, whose upper jaw bones are almost a mirror image of those of the lower jaw. This curious symmetry has been pointed out long ago by the American paleontologist A.S. Romer in early... 

As discussed in detail in Chapter 3.1, the advantage of bioinert materials is that they do not release any toxic constituents to the human body environment. However, on the downside they do not show positive interaction with living tissue. Instead, the body usually responds to these materials by forming a non-adherent fibrous capsule of connective tissue around the bioinert material that in the case of bone remodelling manifests itself by a shape-mediated contact osteogenesis. Consequently only compressive forces will be transmitted through the bone-biomaterial interfaces ( bony on-growth ). 

The glenoid fossa consists of a small, pear-shaped, cartilage-covered bony depression that measures 39.0 3.5 mm in the superior/inferior direction and 29.0 zb 3.2 mm in the anterior/posterior direction [lannotti et al., 1992]. The anterior/posterior dimension of the glenoid is pear-shaped with the lower half being larger than the top half. The ratio of the lower half to the top half is 1 0.80 0.01 [lannotti et al.,... 

The orbit is defined as the anatomic space in the skull that contains the eyeball and its accessory organs. At the orbital apex, many nerves and blood vessels pass from the orbit into the cranial cavity and vice versa. The orbit is pyramidal in shape, with four bony walls narrowing posteriorly toward the apex. 

Inferiorly, the orbital floor covers the top of the maxillary antrum and sinus. The orbital floor and the medial orbital wall are the weakest parts of the bony orbit. The orbital floor is shaped by the maxillary, zygomatic, and palatine bones. 

In the process of evolution, the bony spinal column developed in animals (quadrupeds) for a horizontal alignment. Since primates adopted the vertical posture there has not been sufficient time for the human spinal column to adjust its anatomy to accommodate a vertical alignment. The present shape of the human spinal column is inappropriate for a vertical alignment resulting in considerable disadvantages in human activities. 

The sacroiliac articulations are kidney-shaped and convex ventrally. The sacral and iliac articulations seem to match in a crescent-shaped, convex-concave arrangement, but this is not true for the joints entire bony relationship. Horizontal sections from various levels of the sacroiliac articulation show that the convex-concave relationship exists only at the upper and middle portions. In the lower portion, the relationship is variously described as a flattened, planar joint or a reverse, concave-convex relationship (Fig. 57-1) anatomists differ in their descriptions of the sacroiliac articulations. 

The costochondral region of a rib consists of a concave pit on the end of the bony portion, to which is attached the cone-shaped cartilage. 

---